The present invention relates to an electronic timepiece having a transmission wheel rotational position detecting apparatus for detecting a position along a rotational direction of a wheel, such as a transmission wheel, included in a wheel train, such as an obverse train or a calendar train, of the electronic timepiece.
In a conventional electronic timepiece, as shown by FIG. 38, a portion of an obverse wheel train 930, for example, a 24-h contact point 932 for detecting a rotational position of the obverse wheel train 930 is provided on an hour wheel. When the 24-contact point 932 detects a position in correspondence with twelve o""clock at night, a circuit block 934 rotates a date driving motor 936 by a detection signal outputted from the 24-h contact point 932. By rotating the date driving motor 936, a date indicator 912 is rotated via rotation of a reduction wheel train 938. Thereby, display of date can be changed.
According to such a conventional electronic timepiece, a conduction pin is provided at a region proximate to an outer peripheral portion of a gear portion of the hour wheel. Further, there is constructed a constitution in which when the hour wheel is rotated, the conduction pin is moved to thereby bring a contact point spring into contact with a contact point pattern of the circuit block, thereafter, when the hour wheel is further rotated, the conduction pin is detached from the contact point spring and the contact point spring is detached from the contact point pattern of the circuit block. That is, the contact point spring corresponds to the 24-h contact point 932 and is constituted to detect a position in correspondence with twelve o""clock at night when the contact point spring is brought into contact with the contact point pattern of the circuit block.
Further, according to a structure in which by rotating the date driving motor, a date driving wheel is rotated via rotation of an intermediate date driving wheel and a date indicator is rotated by rotating the date driving wheel, teeth shape of gears of the intermediate date driving wheel, the date driving wheel and the date indicator are constituted by a circular arc gear shape including one or more of circular arcs.
Accordingly, when the date indicator is exerted with an external force such as impact, rotation of the date indicator is hampered only by index torque of the date driving motor.
However, according to the conventional electronic timepiece, there pose the following problems.
(1) The contact point spring is formed by a material which is easy to flex and therefore, it is difficult to position a portion of the contact point spring which is brought into contact with the contact point pattern.
(2) A large space is needed to arrange a contact point spring having a sufficient length of the spring.
(3) When the portion of the contact point spring which is brought into contact with the contact point pattern is arranged remote from the contact point pattern more than necessary, even when the hour wheel is rotated, the contact point spring cannot be brought into contact with the contact point pattern of the circuit block by the conduction pin and time display or calendar display cannot be carried out accurately.
(4) When the portion of the contact point spring which is brought into contact with the contact point pattern is arranged proximate to the contact point pattern more than necessary, in the case where the hour wheel is rotated, pressure of the contact point spring applied on the conduction pin is increased, a malfunction may be caused in operating the electronic timepiece, or the electronic timepiece may be stopped.
(5) The structure of the hour wheel becomes complicated and the contact point spring having a sufficient spring length is needed.
(6) According to the conventional electronic timepiece with calendar provided with the 24-h contact point for detecting the rotational position of the obverse wheel train at a portion of the obverse wheel train, a number of wheel trains are arranged between the obverse wheel train and the date indicator and therefore, it has been difficult to accurately set the position of the date indicator owing to backlashes of the respective wheel trains.
(7) It has been difficult to promote an accuracy for detecting the position of the hour wheel along the rotational direction.
(8) There has been a concern of rotating the indication wheel or the date indicator when the electronic timepiece is exerted with external force by impact or the like. In order to hamper such a positional shift of the date indicator, index torque (stationary state maintaining force: a torque resisting against being rotated in a stationary state) needs to increase. However, when the index torque of the motor is increased, power necessary for driving the motor is also increased and battery life of the electronic timepiece is reduced.
Hence, in order to resolve such conventional problems, it is an object of the invention to provide an electronic timepiece having an apparatus of detecting a rotational position of a transmission wheel for accurately detecting a position of the transmission wheel along a rotational direction thereof.
Further, it is another object of the invention to provide a small-sized electronic timepiece having an apparatus of detecting a rotational position of a transmission wheel.
Further, it is another object of the invention to provide a small-sized thin-type electronic timepiece with calendar.
Further, it is another object of the invention to provide an electronic timepiece having an apparatus of detecting a rotational position of a transmission wheel having high durability function of a contact point.
Further, it is another object of the invention to provide an electronic timepiece having a date driving mechanism and an indication wheel detecting mechanism which are small-sized and simplified.
Further, it is another object of the invention to provide an electronic timepiece with no concern of rotating an indication wheel or a date indicator even when the electronic timepiece is exerted with external force such as impact.
According to the invention, there is provided an electronic timepiece characterized by comprising a transmission wheel rotated based on rotation of a wheel train included in an electronic timepiece and a contact point spring fixed to the transmission wheel and rotated integrally with the transmission wheel and having a conductivity, wherein the contact point spring is constituted to extend substantially linearly by passing through a rotational center of the transmission wheel, further comprising a first detection pattern and a second detection pattern constituted to be capable of being brought into contact with the contact point spring when the contact point spring is rotated, wherein the first detection pattern and the second detection pattern are arranged to constitute an angle of substantially 180 degree relative to the rotational center of the transmission wheel.
The electronic timepiece according to the invention is constituted such that when the transmission wheel is rotated and the contact point spring is brought into contact with the first detection pattern and brought into contact with the second detection pattern, a rotational position detecting signal is generated.
By this construction, the rotational position of the transmission wheel can be detected by using small-sized and simplified parts.
Further, according to the invention, there is provided an electronic timepiece characterized by comprising a transmission wheel rotated based on rotation of a wheel train and a contact point spring fixed to the transmission wheel and rotated integrally with the transmission wheel and having a conductivity, wherein the contact point spring is constituted to extend substantially linearly by passing through a rotational center of the transmission wheel, further comprising a first detection pattern and a second detection pattern constituted to be capable of being brought into contact with the contact point spring when the contact point spring is rotated.
The electronic timepiece is constituted such that the first detection pattern is arranged to constitute an angle of substantially 30 degree relative to the rotational center of the transmission wheel, the second detection pattern is arranged to constitute an angle of substantially 320 degree relative to the rotational center of the transmission wheel, and when the transmission wheel is rotated and the contact point spring is brought into contact with the first detection pattern and brought into contact with the second detection pattern, a rotational position detecting signal is generated.
Further, according to the invention, there is provided an electronic timepiece comprising a transmission wheel rotated based on ration of a wheel train included in the electronic timepiece and a contact point spring fixed to the transmission wheel and rotated integrally with the transmission wheel and having a conductivity. The contact point spring extends substantially linearly by passing through a rotational center of the transmission wheel. A first detection pattern and a second detection pattern are brought into contact with the contact point spring when the contact point spring is rotated. A first dummy pattern and a second dummy pattern are brought into contact with the contact point spring when the contact point spring is rotated. The first detection pattern and the second detection pattern are arranged to constitute an angle of substantially 180 degree relative to the rotational center of the transmission wheel.
The electronic timepiece according to the invention is constituted such that when the transmission wheel is rotated and the contact point spring is brought into contact with the first detection pattern and brought into contact with the second detection pattern, a rotational position detecting signal is generated and the rotational position detecting signal is not generated when the transmission wheel is rotated and the contact point spring is brought into contact with the first dummy pattern and is brought into contact with the second dummy pattern.
By the foregoing construction, the rotational position of the transmission wheel can accurately be detected.
Further, according to the invention, there is provided an electronic timepiece characterized by comprising
a transmission wheel rotated based on rotation of a wheel train included in the electronic timepiece and a contact point spring fixed to the transmission wheel and rotated integrally with the transmission wheel and having a conductivity, wherein the contact point spring includes a first contact point spring terminal and a second contact point spring terminal and a third contact point spring terminal extended outwardly from a rotational center of the transmission wheel.
Preferably, the electronic timepiece is constituted such that the first contact point spring terminal and the second contact point spring terminal are provided to constitute an angle of substantially 75 degree, the first contact point spring terminal and the third contact point spring terminal are provided to constitute an angle of substantially 142.5 degree, the second contact point spring terminal and the third contact point spring terminal are provided to constitute an angle of substantially 142.5 degree.
The electronic timepiece according to the invention is provided with a first detection pattern and a second detection pattern and a VDD pattern constituted to be capable of being brought into contact with the contact point spring when the contact point spring is rotated.
Further, preferably, the first detection pattern is provided within an angle of substantially 30 degree relative to the rotational center of the transmission wheel and the second detection pattern is provided within an angle of substantially 30 degree relative to the rotational center of the transmission wheel.
Further, according to the electronic timepiece of the invention, the VDD pattern includes a first pattern portion and a second pattern portion. Preferably, the first pattern portion of the VDD pattern is provided within an open angle of substantially 60 degree relative to the rotational center of the transmission wheel. Further, preferably, the second pattern portion of the VDD pattern is provided within an open angle of substantially 240 degree relative to the rotational center of the transmission wheel.
Further, one end portion in a circumferential direction of the first pattern portion of the VDD pattern is contiguous to the first detection pattern with a clearance therebetween and other end portion in the circumferential direction thereof is contiguous to the second detection pattern with a clearance therebetween, one end portion in the circumferential direction of the second pattern portion of the VDD pattern is contiguous to the first detection pattern with a clearance therebetween and other end portion in the peripheral direction thereof is contiguous to the second detection pattern with a clearance therebetween.
Thereby, according to the electronic timepiece of the invention, the first detection pattern, the first pattern portion of the VDD pattern, the second detection pattern and the second pattern portion of the VDD pattern are provided in this order in the circumferential direction centering on the rotational center of the transmission wheel.
Further, the electronic timepiece according to the invention is constituted such that a rotational position detecting signal is generated by conducting the first detection pattern and the second detection pattern and the VDD pattern by the contact point spring by rotating the transmission wheel.
Further, according to the electronic timepiece of the invention, there is provided a control circuit for determining to discriminate regular rotation or reverse rotation of the transmission wheel by whether the first detection pattern and the VDD pattern are conducted before conducting the first detection pattern and the second detection pattern and the VDD pattern or whether the second detection pattern and the VDD pattern are conducted before conducting the first detection pattern and the second detection pattern and the VDD pattern.
By the foregoing construction, the rotational direction of the transmission wheel can accurately be determined.
Further, according to the invention, the electronic timepiece is constituted to include the transmission wheel for transmitting rotation to an indication wheel and the contact point spring constituted to rotate integrally with the transmission wheel.
According to a preferable embodiment of the invention, the indication wheel is a date indicator and the transmission wheel is a date driving wheel arranged to rotate the date indicator.
According to the electronic timepiece, the contact point spring includes a first contact point portion extended in a first direction and a second contact point portion extended in a second direction.
Further, the electronic timepiece is provided with a contact point pattern constituted to include a reference potential pattern and a contact switch pattern.
The electronic timepiece is characterized by being constituted such that by rotating the transmission wheel, a rotational signal is not outputted in a state in which both of the first contact point portion and the second contact point portion are brought into contact with the reference potential pattern, the rotational signal is outputted in a state in which the first contact point portion is brought into contact with the reference potential pattern and the second contact point portion is brought into contact with the contact point switch pattern and the rotational signal is outputted in a state in which the first contact point portion is brought into contact with the contact point switch pattern and the second contact point portion is brought into contact with the reference potential pattern and the rotational signal is not outputted in a state in which neither of the first contact point portion and the second contact point portion is not brought into contact with the contact point switch pattern.
By the foregoing construction, the rotational position of the transmission wheel included in a calendar wheel train such as a date driving wheel can accurately be determined.